Extract image metadata from Cinder

This patch makes nova extract image metadata if it is present in the
volume dict received from Cinder API.

The volume image metadata is received from Cinder when the
volume_image_metadata Cinder extension is loaded.

This patch is part of the work done on blueprint improve-boot-from-volume
as this metadata will be used when booting instances from volumes
without the need to supply an image just for the metadata. Subsequent
patches will make Nova consider this metadata when booting instances
without and image id.

Change-Id: I9e5925ea4147a41c41f9019933a47c5ccf756747

nova/tests/test_cinder.py

@@ -42,6 +42,11 @@ def _stub_volume(**kwargs):
     volume.update(kwargs)
     return volume
 
+_image_metadata = {
+    'kernel_id': 'fake',
+    'ramdisk_id': 'fake'
+}
+
 
 class FakeHTTPClient(cinder.cinder_client.client.HTTPClient):
 
@@ -82,6 +87,13 @@ def get_volumes_1234(self, **kw):
     def get_volumes_nonexisting(self, **kw):
         raise cinder_exception.NotFound(code=404, message='Resource not found')
 
+    def get_volumes_5678(self, **kw):
+        """Volume with image metadata"""
+        volume = {'volume': _stub_volume(id='1234',
+                                         volume_image_metadata=_image_metadata)
+        }
+        return (200, volume)
+
 
 class FakeCinderClient(cinder.cinder_client.Client):
 
@@ -155,3 +167,9 @@ def test_cinder_endpoint_template(self):
     def test_get_non_existing_volume(self):
         self.assertRaises(exception.VolumeNotFound, self.api.get, self.context,
                           'nonexisting')
+
+    def test_volume_with_image_metadata(self):
+        volume = self.api.get(self.context, '5678')
+        self.assert_called('GET', '/volumes/5678')
+        self.assertTrue('volume_image_metadata' in volume)
+        self.assertEqual(volume['volume_image_metadata'], _image_metadata)

nova/volume/cinder.py

@@ -20,6 +20,7 @@
 Handles all requests relating to volumes + cinder.
 """
 
+from copy import deepcopy
 import sys
 
 from cinderclient import exceptions as cinder_exception
@@ -117,6 +118,9 @@ def _untranslate_volume_summary_view(context, vol):
         item['value'] = value
         d['volume_metadata'].append(item)
 
+    if hasattr(vol, 'volume_image_metadata'):
+        d['volume_image_metadata'] = deepcopy(vol.volume_image_metadata)
+
     return d